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Free keywords:
Dabie Mountains, ultra-high pressure metamorphic belt, Tancheng-Lujiang fault, seismic tomography, wide-angle reflection
DDC:
550 - Earth sciences
Abstract:
In the spring of 1997, scientists from the Chinese Academy of Geological Sciences and GeoForschungsZentrum Potsdam jointly collected seismic reflection data along a line in the Dabie Mountains. The seismic line, about 20 km long, begins west of the Town of Qianshan, crossing the Tancheng-Lujiang Tancheng-Lujiang Fault, and ends up in the ultra-high pressure metamorphic block in the Dabie Mountains area. The experiment mainly explored layered structure of the upper, middle and lower crust. To study the crustal reflectivity, the standard common-depth-point (CDP) experiment was carried out. The tomographic method was applied to provide velocity information for the shallow (≤ 5 km) structure, and the companion wide-angle shots gave control on the velocity structure of the deeper reflectors. The conventional CDP processing resulting in a stacked time section shows a very detailed structure with different reflectors down crust, while to the west in the upper crust, indicating complex evolution of this area. The Moho appears throughout the profile, generally at about 11s TWT. The result from the seismic tomographic image shows that the high velocity bodies might be positioned at a depth of only about 1.5 km below sea level within the Dabie ultra-high pressure metamorphic belt.
